Method for production of cellulose ion exchangers

ABSTRACT

A method for the manufacture of cellulose ion exchangers, such as carboxymethylcellulose, diethylaminoethylcellulose, and ECTEOLA-cellulose, by treating moist disintegrated cellulose with sodium hydroxide solution, etherifying the thus-mercerized cellulose, at an elevated temperature, and thereafter washing the product and dehydrating same with an organic solvent.

United States Patent Khusid et al.

[ 1 3,664,999 51 May 23, 1972 [54] METHOD FOR PRODUCTION OF CELLULOSEION EXCHANGERS [72] Inventors: Iosif Efimovich Khusid, Riga Latviiskoi;

Ljudmila Ivanovna Bezgodova; Mara Khugovna Ruben, both of OlaineLatviiskoi, all of U.S.S.R.

[73] Assignee: Olainsky Zavod Khimreaktivov, Latviiskaya, S.S.R. Olaine,USSR. [22] Filed: Apr. 22, 1968 [21] Appl.No.: 723,260

[30] Foreign Application Priority Data Apr. 22, 1967 U.S.S.R ..1,150,438

[52] US. Cl ..260/231 A, 260/231 R, 260/232, 260/233 [51] Int. Cl...C08b 11/00 [58] Field ofSearch ..260/231 A, 232, 233, 233.3

[56] References Cited UNITED STATES PATENTS 2,667,480 1/1954 Branan etal ..260/231 2,876,217 3/1959 Paschal] ..260/233.3

2,917,506 12/1959 Caldwell et al. ..260/234 2,921,934 1/1960 Weisberg..260/232 3,070,594 12/1962 Harris et al. ..260/233.3 3,226,380 12/ 1965 Knight ..260/212 3,243,426 3/1966 Caesar.... 260/233 3 3,342,8059/1967 Caliban ..260/232 3,379,719 4/1968 Rulison l ..260/231 3,394,1277/1968 Sommers ..260/232 OTHER PUBLICATIONS Peterson et 21., AmericanChemical Society Journal, Vol. 78, Feb 1956, pages 751 through 755.

Primary Eraminer-Dona1d E. Czaja Assistant ExaminerM. I. MarquisAttorneyWaters, Roditi & Schwartz [57] ABSTRACT A method for themanufacture of cellulose ion exchangers, such as carboxymethylcellulose,diethylaminoethylcellulose, and ECI'EOLA-cellulose, by treating moistdisintegrated cellulose with sodium hydroxide solution, etherifying thethusmercerized cellulose, at an elevated temperature, and thereafterwashing the product and dehydrating same with an organic solvent.

5 Claims, No Drawings METHOD FOR PRODUCTION OF CELLULOSE ION EXCHANGERSThis invention relates to methods for the production of cellulose ionexchangers such as carboxymethylcellulose, diethylaminoethylcellulose,and ECTEOLA-cellulose, which find application in biological research, inthe pharmaceutical industry, and in other industrial fields.

There is a known method for the preparation of cellulose ion-exchangeadsorbents, which comprises treating dry cellulose powder with aconcentrated sodium hydroxide solution at a temperature of 46 C.(mercerization), followed by etherification with appropriate agents, andWashing, dehydrating and drying the obtained product.

The known method suffers from the following limitations.

The mercerization step involves technological difficulties, particularlyso at the commencement of the mercerization process when smallquantities of alkali solution at a temperature of 4-6 C. are added tothe bulk of dry cellulose powder and yield a non-homogeneous, locallyalmost solidified, mass which does not lend itself to stirring and tendsto be locally overheated due to poor heat transfer.

The manufacturing process is very elaborate and expensive, insofar as itcalls for the use of dry cellulose powder as feed stock which, prior tomercerization, is dehydrated by means of alcohol and ether, dried andsieved, and thereafter mercerized by treating with aqueous alkali.

The process equipment and flow sheet are complicated, inasmuch as theprocess of mercerization is carried out at a temperature of 46 C. andthe reaction mixture, after completion of the etherification step, mustbe cooled down to 46 C.

The employment of diethyl ether or acetone for dehydrating theprecipitate of cellulose ion exchangers involves tire and explosionhazards.

it is an object of the present invention to simplify the process ofmanufacturing cellulose ion exchangers, to increase the yield of productcompounds, and to provide for an enhanced efficiency of raw materialutilization.

These objects are accomplished by the provision of a method for theproduction of cellulose ion exchangers which comprises treatingcellulose with a sodium hydroxide solution, carrying out theetherification step at an elevated temperature, followed by cooling andwashing the product thus obtained and dehydrating it by means of organicsolvent, the novel feature of the method, according to the invention,being that the cellulose material subjected to alkaline treatmentconsists of disintegrated cellulose having a moisture content of notgreater than 70 percent by weight and a pH equal to or greater than 7.

It is preferable to use cellulose pulp having a moisture content of 60to 70 percent by weight, thereby making it possible to obtain a moremobile homogeneous pulp and to carry out the mercerization step morecompletely and within a shorter time at a temperature of 6 to 12 C.

After the etherification step, the reaction product is cooled to 30 C.prior to its being subjected to further treatment.

To obtain the desired cellulose ion exchanger, use is made of anappropriate etherifying agent. For example, carboxymethyl-cellulose canbe prepared by using a solution of monochloroacetic acid to effectcellulose etherification, while the use of a solution of2-chlorotriethylamine hydrochloride yields diethylaminoethylcellulose. Amixture of epichlorohydrin and triethanolamine is useful for thepreparation of ECTEOLA-cellulose.

Cellulose ion exchangers can be prepared according to the presentinvention not only from dry cellulose powder, but also by using aqueouscellulose paste obtained after washing the cellulose stock from whichdry cellulose powder is to be produced, the employment of aqueouscellulose paste being advantageous inasmuch as it is conducive toreducing substantially the cost price of the finished product.

The present invention makes it possible to simplify the process ofcellulose mercerization as a result of the fact that the incorporationof aqueous alkali into cellulose in the form of an aqueous paste yieldsan adequately mobile mass, so that the mercerization process proceedsunder milder conditions, at a greater rate and more completely than ispracticable when resorting to the known method, the overall result beingthat the yields of product compounds are higher than those obtainablewith dry cellulose powder as the starting material.

Carrying out the mercerization process at a temperature of 6l2 C., asagainst a temperature of 4-6 C., and cooling the reaction mixture downto a temperature of 20-30 C., as against a temperature of 4-6 C.resorted to in the known method, renders possible the use of simplerequipment for cooling the reaction mixture, yields a saving in time andinvolves lower power consumption.

For a better understanding of the invention, the following examples arepresented by way of illustration.

EXAMPLE 1.

One hundred grams of aqueous cellulose paste (on dry weight basis)obtained in the course of manufacturing dry cellulose powder is placedin a 3-1. reactor and into it is stirred 330 ml of a 31 percent aqueoussolution of NaOH at a temperature of 6-12 C. The contents of the reactorare maintained at this temperature for 30 minutes, followed byincorporating thereinto 67 ml. of 43 percent monochloroacetic acid andcarrying out the etherification process at a temperature of 70 to 75 C.for a period of 20 minutes.

Then, the reaction mixture is cooled to 30 C. and into it is stirred 850ml of 10 percent acetic acid followed by acidulation with glacial aceticacid until the pH equals 4 to 5. NaOH.

The reaction mixture is filtered, and the carboxymethylcellulose thusseparated is washed with distilled water until the washings show noacidic reaction and thereafter placed in 2 l of 0.5N HCl for a period of3 hours, washed again with water until the washings show no acidicreaction, dehydrated with 800 ml of absolute ethanol and dried in theair. The yield of carboxymethylcellulose equals 69 g; exchange capacity,0.5 meq per gram.

EXAMPLE 2.

One hundred grams of cellulose powder (on dry weight basis) is dilutedwith water until the moisture content equals 70 percent and placed in a3-1 reactor and treated, while being stirred, with 250 ml of 20% NaOH ata temperature of 6 12 C. The reaction mixture is maintained at thistemperature for 30 minutes and thereafter etherified at a temperature ofC. and for a period of 35 minutes with 175 ml. ofa 25 percent solutionof 2-chlorotriethylamine hydrochloride. Then, the reaction mixture iscooled to 2030 C., 400 ml of 2N NaCl solution is added thereto and theprecipitate is filtered off. The filter cake is washed with 1N NaOH toremove any color, and thereafter with 300 ml of 1N HCl and 300 ml of 1NNaOH, transferred into a beaker into which is charged 2.51. of 0.1 NNaOH and left for 10 hours. The supernatant liquid is decanted and theprecipitate of diethylaminoethylcellulose is filtered off, washed withwater until the washings show no basic reaction, dehydrated with 800 mlof absolute alcohol and dried in the air.

The yield of diethylaminoethylcellulose is 63 g; exchange capacity, 0.6meq per gram.

EXAMPLE 3.

One hundred grams of dry cellulose powder (on dry weight basis) isdiluted with water until the moisture content equals 70 percent byweight, and the resultant aqueous paste is charged in a 51 reactor.

Then, 250 ml of 28% NaOH solution is stirred into the paste at atemperature of 612 C. and the reaction mixture is allowed to stand for20 to 30 minutes, followed by adding thereinto 690 ml of a mixture oftriethanolamine and epichlorohydrin taken in a ratio of 1.3: 1 .0. Thecontents of the reactor are heated on a water bath, maintained at atemperature of l05 C. for 30 minutes, cooled to 30 C., and 400 ml of 2NNaOH solution is added thereto. The precipitate of ECTEOLA-cellulose isseparated, placed in a 1N solution of NaOH for 1 hour and filtered off,followed by washing the filter cake first with 300 ml of 1N HCl and thenwith 300 ml of 1N NaOH. This washing procedure is repeated andthereafter 2.51. of 0.1N NaOl-l is poured onto the precipitate and leftfor hours. The liquid is decanted and the ECTEOLA-cellulose precipitateis washed with distilled water until washings show neutral reaction,dehydrated with 800 ml. of absolute ethanol and dried in the air. Theyield of ECTEOLA-cellulose equals 89 g.; exchange capacity, 0.55 meq pergram.

We claim:

I. A method for the production of cellulose ion exchangers whichcomprises mercerizing disintegrated cellulose having a moisture contentof between 60 and 70 percent by weight with a solution of sodiumhydroxide at a temperature of not below 6 C. and a pH of at least 7 inthe reaction mixture, followed by etherifying the mercerized productwith monochloracetic acid, 2-chlorotriethylamine hydrochloride, orepichlorohydrin and triethanolamine, and thereafter washing, dehydratingwith and organic solvent and drying the cellulose ethers thus obtained.

2. A method according to claim 1, wherein mercerizing is carried out ata temperature of 6l 2 C.

3. A method according to claim 1, wherein the etherification is effectedat a temperature of 70-75 C. with a solution of monochloroacetic acid toproduce carboxymethylcellulose.

4. A method according to claim 1, wherein the etherification is effectedat a temperature of -85 C. with a solution of 2-chlorotriethylaminehydrochloride to produce diethylaminoethylcellulose.

5. A method according to claim 1, wherein mercerized disintegratedcellulose is etherified with a mixture of triethanolamine andepichlorohydrin at a temperature of from to C. to obtain a mixedcellulose ether.

2. A method according to claim 1, wherein mercerizing is carried out ata temperature of 6*-12* C.
 3. A method according to claim 1, wherein theetherification is effected at a temperature of 70*-75* C. with asolution of monochloroacetic acid to produce carboxymethylcellulose. 4.A method according to claim 1, wherein the etherification is effected ata temperature of 80*-85* C. with a solution of 2-chlorotriethylaminehydrochloride to produce diethylaminoethylcellulose.
 5. A methodaccoRding to claim 1, wherein mercerized disintegrated cellulose isetherified with a mixture of triethanolamine and epichlorohydrin at atemperature of from 90* to 105* C. to obtain a mixed cellulose ether.